a. Field of the Invention
The present invention relates to gravity tables, and in particular, to gravity tables used to separate materials of different sizes, weights, specific gravities and bulk densities, and systems to automate operation of gravity tables.
b. Problems in the Art
One mechanized method for separating materials of different qualities is the gravity table. This method is widely used in a variety of different separation processes. For example, it can be used to separate granular materials such as seeds, minerals, coffee, beans, etc. Gravity separators can classify materials by size, weight, specific gravity and bulk density; can separate chaff or other low density particles from higher density particles, such as in grain cleaning; and can improve germination of seeds by separating good quality, heavier seeds from low quality, diseased, or damaged lighter seeds. These are but a few of the many uses for gravity separators. Examples of other separation processes include, but are not limited to, separation of bones from meat and separation of copper from aluminum.
Gravity separators can take many forms and embodiments. Examples of gravity separators can be found in U.S. Pat. Nos. 3,888,352; 3,406,824; and 3,693,794; and are incorporated by reference herein as showing the general operating principles of gravity separators.
Although gravity tables are generally efficient in result, they are quite complex to operate to maximum efficiency. Conventional gravity tables generally have a number of operational adjustments which can alter the reliability of separation results. For example, the gravity table generally slopes in one or more directions between the entrance and discharge ends of the table. Many times the table is sloped in two directions; namely, downwardly from entrance to discharge, and downwardly transversely across the line from entrance to discharge. The table is also usually fluidized by air, either positively forced through perforations in the bottom of the table, or by suction above the table. The feed rate of the materials entering the table can also be adjusted. Finally, both the speed of vibration of the table, and the magnitude of vibration can generally be adjusted.
It can therefore be seen that alteration of one of these adjustments could materially affect the overall operation of the table. Furthermore, the adjustments are interrelated and the table has to be adjusted for different types of materials. A skilled operator is therefore required to make the table function to optimum efficiency.
Additional problems exist in that external factors also affect operation of the table. For example, air temperature and humidity significantly affects separation of materials such as seeds. Any changes in these factors can materially affect the reliability of separation results. Also, most times the material being separated does not have consistent properties during its separation, or between its initial feeding onto the table, and its ultimate separation. Finally, continuous operation of the machine also might alter the functioning of separation.
If the gravity table is misadjusted, excessive amount of good product may be lost with the discard from the gravity table or the undesirable product may be mixed with the good product resulting in poor quality. Both situations will result in adverse effects and possible loss of economic revenue for a company using such a gravity table.
Thus, gravity tables must constantly be monitored and adjusted to achieve optimum results. This requires significant skill of the operator, and comprehensive surveillance by the operator. Training and labor costs are therefore substantial.
These costs could be reduced if gravity tables could be automated.
It is therefore a principal object of the present invention to solve or improve over the problems and deficiencies in the art.
A further object of the present invention is to provide a means and method of gravity table automation which provides objective indication of a gravity table's operation.
Another object of the present invention is to provide a means and method as above described, which detects whether the gravity table is generally functioning to its desired level.
Another object of the present invention is to provide a means and method as above described which utilizes a detector means and control particles to continuously monitor operation of the table.
A further object of the present invention is to provide a means and method as above described which can be utilized to completely automate operation of the gravity table.
Another object of the present invention is to provide a means and method as above described which is efficient, economical, reliable and durable.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.